page_alloc: fix kernel-doc warning

Ummark function as having kernel-doc notation, fixing the kernel-doc
warning.

Warning(mm/page_alloc.c:4519): No description found for parameter 'zone'
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/page_alloc.c

@@ -4541,7 +4541,7 @@ void setup_per_zone_wmarks(void)
 	calculate_totalreserve_pages();
 }
 
-/**
+/*
  * The inactive anon list should be small enough that the VM never has to
  * do too much work, but large enough that each inactive page has a chance
  * to be referenced again before it is swapped out.